Spouse's Voice Aids Hearing in 'Cocktail Party' Noise

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As people get older and their hearing worsens, they have more
difficulty understanding speech in noisy environments, but recent
studies suggest that familiarity with certain voices can partly
compensate for poor hearing.

"When you get older, your hearing
declines, your vision and memory decline. But what older
people have a lot of is knowledge and experience," and this can
help them, said Ingrid Johnsrude, a professor of psychology at
Queen's University in Ontario, who studies speech perception and
aging.

Listening to a single conversation amid a noisy environment
challenges the brain's auditory system – yet somehow, people are
able to tune into the sound of a single voice, understand it and
follow a conversation. This phenomenon is called the "cocktail
party effect." [ Top 10 Mysteries of the Mind ]

In studying the effect, scientists have focused on the factors
that help the brain tease out voices from a mixture of sounds
arriving to the ear. Researchers have looked at the pitch of the
voices and where the speakers are located relative to the
listener, among other factors.

However, recent research shows that the brain does not rely only
on the incoming sounds themselves to understand speech, but also
uses information from other senses, as well as past experience.
Those findings come from research Johnsrude presented last month
at a meeting of the Canadian Association for Neuroscience in
Montreal.

Who you choose to talk to matters

In their experiments, Johnsrude and colleagues had participants
listen to speech amid interfering voices and noise, and examined
how the participants' attention, familiarity with the voices and
knowledge of what was being said helped them understand the
speech.

In one of these studies, the researchers looked at middle age and
elderly couples who had been married for at least 18 years.
Published in the journal Psychological Science in 2013, the study
found that people are more successful in focusing on a voice and
blocking out noise if the voice belongs to
their spouse.

"We found that older people really benefit a lot from having a
familiar voice in the mix," Johnsrude told Live Science. "Not
only do they hear that voice better than a matched stranger's
voice, but they can also use the voice they know to ignore it so
as to attend to another voice more easily."

Knowledge helps

Knowledge about the context of the conversation can also help
people understand hard-to-hear
speech. In a series of experiments, Johnsrude and colleagues
had participants listen to a sentence that was read in the
context of bad-quality sound, while also seeing the text of the
sentence. Each word of the sentence appeared, one by one and on a
screen, 200 milliseconds before the word was heard.

Looking at brain scans, the researchers found that reading the
sentence was linked to a greater change in the activation of the
brain's primary auditory cortex, which handles incoming auditory
signals, compared to seeing a meaningless string of consonant
letters shortly before hearing each word.

"The auditory cortex was sensitive to the difference between
getting that meaningful information visually and not getting it.
And we know the auditory cortex doesn't read," Johnsrude said.
"So that modulation based on what you read must be coming from
somewhere else in the brain." The
findings were detailed in the journal Neuroimage in
2012.

Learning from the brain

Researchers have explored the role of knowledge and experience in
influencing perception in other senses such as the visual and
olfactory systems. For example, people can more easily figure out
a scrambled picture if they know what to look for, and they take
less time to identify odors they have smelled previously.

The auditory system seems to be no exception, and for older
people, this can come handy, Johnsrude said.

"If we are looking at ways to help older people, or if we want to
understand how they are able to perceptually organize their world
despite diminished hearing, we need to understand how knowledge
and experience can influence their performance," Johnsrude said.